C/C++ :: Why To Use Private Fields In A Class
Aug 9, 2014Why do you use Private fields in a class if an outside class can change the private fields using get and set properties?
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C :: How To Create Private Fields In A Struct
Nov 6, 2014How can you actually create private fields in a C struct? I got the concept of VTable and inheriting methods aswell overriding them, but private variables can be obtained with static keyword in sourcefile. If you have variables in a struct, you can access them as soon as you got a ref to the struct. The functions are easy:
Code:
struct classA {
pointerToFunction *p;
} static void* thePrivateFoo() { }
void* publicFoo() {
thePrivateFoo(); /* or something like that */
} ...
/*in init code somewhere in the c file */ classAInstance->p = publicFoo;
But I was thinking about the variables... How is this achievable? I was thinking of a struct with only get/set functions and with no datamembers at all. All vars to be static outside the struct. But this kind of destroys the encapsulation.
C# :: Method Of Mapping Text File Dictionary To Class Fields
Jan 21, 2014So I'm rewriting an old project of mine, and I'm trying to determine if there's truly any better way to map the data taken from a text file "dictionary" into the correct class fields for further processing. For example:
FNAME=MY_FIRST_NAME
ADDR=123 SOMEWHERE LN, NOWHERESVILLE, TX 01234
LNAME=MY_LAST_NAME
TOTCALLS=47
In each of these, I'd need the "value" (MY_FIRST_NAME, MY_LAST_NAME, etc) from the "keys" (FNAME, LNAME, etc) to be mapped to the proper class fields. Say, for example, I had this:
Class DataProcessing {
public string Address;
public string FirstName;
public string LastName;
public int TotalCalls;
...
}
I would need DataProcessing.Address to be set to the value in the ADDR key/value pair. The same would be true for each other field. The problem is that based on the text file's source (which isn't under my control, and won't be changed anytime soon), the key/value pairs are not always in the same place...so a second file could have the data as such:
TOTCALLS=47
ADDR=123 SOMEWHERE LN, NOWHERESVILLE, TX 01234
LNAME=DARKPOETCC'S LAST NAME
FNAME=DARKPOETCC'S FIRST NAME
Any smarter way to do this than looping through each line that was read in from the file, and determining where it belongs, such as (pseudo code follows):
IF FieldName == "TOTCALLS" THEN
//Assign to TotalCalls field
ELSEIF FieldName == "ADDR" THEN
//Assign to Address field
ELSEIF FieldName == (You get the picture...)
//Do thing N_Field
C++ :: Cannot Access Private Member Declared In One Class But Can In Another Class
Sep 4, 2014So I have an ImageManager class, Board class, and Box class. In Board.h I can declare ImageManager imgr; and in Board's constructor I can use imgr and its functions and such. However, in Box.h when I try and declare ImageManager imgr; I get the error "cannot access member declared in class ImageManager". Both declarations are under private, and exactly the same, but one doesn't work. Also, is there a way to only have one instance of ImageManager?
View 19 Replies View RelatedC/C++ :: Accessing Private Class?
Apr 4, 2014I am trying to access the private member from main . The code is as follow. I wanted to call below function from main.
uint16_t Modbus::calcCRC(uint8_t u8length)
#define MAX_BUFFER 64
typedef struct {
[Code]....
C/C++ :: Data In Private Class
Dec 11, 2014i have private data look like Peiceorder peiceOrders[20]; it looks like a array but does not have name type like int or char? why is that and what should I use the data should I write Peiceorder peiceOrders[20]=........ like that? or?
View 1 Replies View RelatedC++ :: Unable To See Enclosed Private Class
Oct 30, 2013I have a class (Quadtree) and three inner class inside (Node, Inner and Leaf). Inner and Leaf inherit from Node.
I have a function in the private scope of Quadtree.
All these are located in fun.h .
Then, in fun.cpp, I am implementing the function (which is named foo <- what a prototype name!), which takes as argument a pointer to an Inner object. Inner seems unable to be resolved however!
fun.h Code: class Quadtree {
private:
class Node{
public:
Node() { std::cout << "Node
"; }
};
class Inner : public Node {
public:
Inner() { std::cout << "Inner
[code]....
C++ :: Private Global Variable To Class?
Sep 30, 2014I want to make a destructor counter...So it needs to be outside that specific instance of the class. And i want to keep it hidden. I don't want to be able to access it from outside the class...I Don't want main.cpp to have access to this variable
Is there a way to do this?
static int destructorCount;
C++ :: Vector As Private Class Member
Feb 16, 2013I get a problem with the vector as a private class member: When I did't initialize the vector in constructor(which means the size of the vector would be 0), I used a class function to add two elements to the vector and it worked (because I added a "printf" to output the size of the vector and the elements within that function). However, when I used another class function to visit that vector, no element was in and the size became 0.
Then I tried to add two elements to the vector during the construction, and it turned out that these two elements could be stored in the vector while other elements added through class functions could not.
I guess there may be some problems on the scope of the function. But I feel the class member should not be effected by the scope of the class function.
C++ :: Access To Private Member Map Outside Class
Oct 24, 2013This question is more from a design point-of-view rather than coding it to be a fully functional.
So here it goes:
I have multiple files which each require their own object of same class type (ref. First Class). File contents are read from a file to a unordered_map<std::string, std::vector<std::string>> which is either private or protected member inside First Class. First Class does not need any public functions to add, remove or change the data during runtime, but changes are only being made by checking if the file size has changed during the day, if the size is not equal to the last check, map gets updated.
Now, I have a Second Class which is a data handler class. It has public member functions with arguments that needs to be get from First Class's unordered_map using const_iterator. Which way to go with design and implementation.
I know there's two methods to do this. Re-doing handler class is also not out of the question. These two methods I'm aware of are:
1. Declare these maps to local scope, build few global functions and here we go. (Probably the easiest way.)
2. Create public member functions to a First Class which either return a pointer or a reference to a protected/private member. (I'm under the impression that I really shouldn't be doing this because of a bad coding practice.)
Note that I don't need any code here, just some other point-of-views regarding the subject itself for learning better coding practices.
C++ :: Why Class Members Private By Default
Apr 14, 2013The reason that class members are private by default is because, in general, an object of a class should be a self-contained entity such that the data that make the object what it is should be encapsulated and only changed under controlled circumstances. Public data members should be very much the exception. As you’ll see a little later in the chapter, though, it’s also possible to place other restrictions on the accessibility of members of a class.
View 17 Replies View RelatedC++ :: 3D Game - Getting Private Var From Other Class (GLfloat)
Mar 10, 2013I'm trying to make a 3d game. I just started with opengl in c++ but I ran into a problem. What I have now.
Creating the array:
std::vector<Bullet*> bulls;
In the display function:
for (unsigned int i=0; i<bulls.size(); i++) {
[Code] ....
But when I try to compile this it gives an error:
cannot convert ‘Bullet::Get_prevx’ from type ‘GLfloat (Bullet::)() {aka float (Bullet::)()}’ to type ‘GLfloat {aka float}’
C++ :: Public And Private Functions With No Class?
Jul 7, 2012I've been writing my own implementation of quicksort in a .h file. I've gotten to the point where I think I'm done with the algorithm, so now I'm trying to make it so that if someone includes "quicksort.h", they will only have access to certain functions in the file. Kind of like public and private functions in a class, but without the "class" part of it. How do you do that?
View 7 Replies View RelatedVisual C++ :: Class / Private - Reading Uml?
Feb 9, 2013So I'm trying to do a homework assignment, where I read a uml about a bank program, and just create it. Here is the UML. So while working on Bank, the top one, i've come up with this so far.
Code:
#include <iostream>
#include <string>
using namespace std;
class bank
{ string name;
int routingNum;
[Code] ....
I'm assuming that's what the uml wants. However I can't seem to access that private class. Idk why. I declared it as an object in the main.
C++ :: Cannot Access Private Member Declared In Class
Aug 22, 2013I have a method:
int filetodb(std::wstring szwf, SQLHANDLESTR *h);
I want to use it, in a thread.
std says, use thread, as:
std::thread second (bar,0); // spawn new thread that calls bar(0)
How can I do this, for my method, that uses more than one, i.e., two, parameters?
My code is:
std::thread thread = std::thread(filetodb, filesP->at(i), h);
compiler says:
Error10error C2248: 'std::thread::thread' : cannot access private member declared in class 'std::thread'c:program files (x86)microsoft visual studio 11.0vcincludexmemory06061ConsoleApplicationa
How, can I do this?
C++ :: Cannot Define Method Of Inner Nested Class If It Is Private
Jan 16, 2013it seems that I cannot define a method of an inner nested class if it is a private class. for example:
class outter {
class nested {
void foo ( void ) {} // okay - but is this inline?
} void inner::foo( void ) {} // not okay - cannot define inside another class
} void outter::inner::foo( void ) {} // not okay - 'nested' class is private!
what I want to know is, is there another way to define an inner class's method? and if not, is it eternally doomed to be inline because it has to be declared inside it's own class declaration?
C++ :: Accessing Private Members From Inside Class
Jan 10, 2013Let's say I have the following class:
class MyClass {
private:
int m_myInt;
public:
int myInt() {return this->m_myInt;};
int myFunc();
};
Which of the following is to prefer;
int MyClass::myFunc() {
return 2*this->m_myInt;
}
or
int MyClass::myFunc() {
return 2*this->myInt();
}
The second one seems better? Are both OK? What's the best practice?
C++ :: Private Inheritance Multiple Times From Same Class
Sep 19, 2014I've been working on a program that uses a reference counting class that I've written which works fine for objects that inherit from it however I now need to have the following setup:
class SBComponent : private Refcounted { /*stuff*/}
class ProxiedComponent : public SBComponent, private Refcounted {/*stuff*/}
The compiler gives the following warnings
warning: direct base ‘Refcounted’ inaccessible in ‘ProxiedComponent’ due to ambiguity
And then several repeats of the error:
error: request for member ‘bk’ is ambiguous
Back *b = bk<ProxiedComponent>();
bk is a templated function that's defined in Refcounted and returns a pointer of type <template arg>::Back (ProxiedComponent::Back in this case).
I don't understand why the call to bk is ambiguous as although there's two instances of Refcounted (there needs to be with the way I've designed it so I can't make it virtual) it's inheritance is private in both cases so there should only be one instance of it visible in ProxiedComponent.
C++ :: How To Make Private Member Accessible Outside Class
Aug 9, 2013The question says that:
#include<fstream.h>
#include<conio.h>
#include<stdio.h>
#include<string.h>
[Code].....
But then the 2nd part of the question itself says that "Acno entered by the user". So we need to identify/search for an account with that Account Number. How can we do this without comparing Acno with S.Acno? I know that S.Acno is not accesible as it is a private member but then how to compare Acno without even using a member function(public) that can return the value of Acno?
C++ :: Why Private Member Template Accessible Outside Class
Jan 15, 2015I just happened to find that a nested private template class can be accessed directly outside the enclosing class using a using alias:
namespace ns {
class __wrapper
{
private:
[Code].....
I was hoping to see a "__wrapper::__tklass is private" error message in the first using statement as well as during the instantiation of ns::tklass, but no error is issued. I tried this on gcc-4.9.2, clang-3.5.0 and visual_studio 2013 express.
why exactly doesn't the compiler flag tklass as an error? Is it allowed by the standard? If so, wouldn't that be a serious access violation?
C++ :: Accessing Private And Protected Member Functions Of Class?
Mar 30, 2013how to access the private and protected member functions of the class.....
View 5 Replies View RelatedC++ :: Declaring Vector Of Pointer As Private Class Member
Mar 6, 2013Below is a working program. Please note that the vector <int*> pointer is declared as a public member of the class A.
The problem arises when I try to make it a private (instead of public). First, let's look at the File 1 below. It compiles and works fine.
File 1: main.cpp (working fine)
#include <vector>
#include <iostream>
using namespace std;
[Code].....
C/C++ :: Defining Class Counter - Member Variable Should Be Private
Oct 23, 2014The question is: Define the class Counter. An instance of this class is used to count things, but the counter should never be less than 0 (non negative number). The member variable should be private. I realize what I'm suppose to be using but can't implement the member functions needed..
int main(){
int value;
cin >> value;
Counter myCounter(value);
for (int i = 1; i <= MAXLOOP; i++) {
myCounter.increment();
[Code] ....
C++ :: Create Assignment Operator For A Class That Uses Pointer For Its Private Variable?
Mar 30, 2013i am trying to create the assignment operator for a class that uses a pointer for it's private variable. The error is saying expected constructor, deconstructor, or type conversion before "operator. (which is the assignment operator. I have tried everything i could think of or find online and nothing has worked. below is the code for the assignment operator in the .h file and the .cpp file.
//Assignment constructor
indexList &operator=(const indexList <T> &rhs);
template <class T>
indexList<T>::indexList operator=(const indexList <T> &rhs) {
if(this != &rhs) {
numberOfElements = rhs.numberOfElements;
[Code]...
C++ :: Boost Threading - Cannot Access Private Member Declared In Class
Feb 25, 2013When I put boost::thread Thread; in my struct I get the error error C2248: 'boost::thread::thread' : cannot access private member declared in class 'boost::thread'
The whole struct is
struct Player {
bool key[256];
char nameString[64];
bool lMouseButton;
bool rMouseButton;
double mouseX;
double mouseY;
[Code] ....
C++ :: Cannot Access Private Member Declared In Class (header File)
Apr 1, 2014I am currently doing the assignment about linked list. Here are some details information about what I am doing.. This program is C++ and should run on Visual Studio 2010. And it contains three file, two datastructure header and one main cpp file.
This program is trying to arrange and show some sports records. The main program which contain the functions such as reading the result text file(each result text file contain several records of athletes), removing a file, arranging the totalresult and printing it out. And the main program is already given and I cannot overwrite it.
But when I finished and try to build the solution and run it, I am not able to run the program and it give me somethings like these...
warning C4172: returning address of local variable or temporary
error C2248: 'Datastructure1::Datastructure1' : cannot access private member declared in class 'Datastructure1'
see declaration of 'Datastructure1::Datastructure1'
see declaration of 'Datastructure1'
This diagnostic occurred in the compiler generated function 'Result::Result(const Result &)'
And I have tried to comment each function part of the header file and see if can run or not. But I still fail to do so. Here are my codes...
#ifndef DATASTRUCTURE1_H
#define DATASTRUCTURE1_H
class Datastructure1 {
Public:
Datastructure1( );
[Code] ....
There are two header files and look quite long. They are all some linked list functions . I have read and learn linked list data structure before I complete this programs. However, when I complete the functions required, the function cannot be compile....